This invention relates generally to fire detectors and more particularly to a fire-detection system which provides optimum sensitivity to a threat of fire and minimizes the occurrences of false alarms during changing environmental conditions.
Existing fire and smoke detectors perform satisfactorily in a relatively constant environment. However, when these detectors are exposed to a frequently changing environment, such as a machine shop, rooms containing smoking personnel and/or machines which emit oil, smoke, or other particulate matter, or abroad ship where various locations encounter temperature, humidity, and air flow extremes, they produce a high percentage of false alarms in comparison to actual threats of fire, and thus perform unsatisfactorily. Also, under such changing environmental conditions, existing fire detectors may require frequent servicing due to the collection of particulates within a detector.
Some existing fire and smoke detectors compare output signals of sensors with a preselected threshold signal level and sound an alarm if the output signals exceed the threshold level. The greater the sensitivity of such detectors, the more the detectors may give false alarms. If such detectors are adjusted to a lower sensitivity, a threat of fire may be allowed to escalate.